Piazza san Marco is composed of two adjoining spaces: the large open space focused on the west elevation of San Marco and the small square which joins the larger to the open lagoon or the 'Piazzatta di San Maraco'. Together these form one of the most famous and imposing squares of the world. Both Sansovino and Baldassare Langhena are responsible for most of what we see today with respect to the continuous arcades on the west and north flank, most completed between 1578-1634.